BNR S3 or BNR S4
 

Hey everyone, I searched and couldn't find a dedicated thread comparing the these two turbochargers. I'm looking into upgrading the stock K04 with either a BNR S3, or a BNR S4 simply because of their good reviews, price, and simplistic installation. I'm leaning more towards the S4 because it opens up more possibilities in the future for more power to be made.

How do they compare in terms of:
- Reliability
- Ease of installation
- Efficiency (max boost before being overworked)
- Spool characteristics (rpm wise)

And is there a parts list available for all the required parts to run either setup safely and efficiently?

Thanks any input is appreciated.

Without a single hesitation, S4. I wouldn't even think twice about it. I've had a BNR S3 for a few years. The BNR S4 spools as quickly as the S3 and flows an extra ~5lbs/min on the top end and it doesn't have to work as hard as the S3 to do it.

In other words, with an S4 you give up nothing and get more and the install is just as easy. I've been contemplating an S4 myself after seeing the dyno plots of that S4. They give me tingly feelings.

Haha I bet they do, and the price difference isn't that much between the two on the rpm store website. I'm probably going to go with the S4 because it seems there are no downsides.

List of required parts for an S4 setup:
- 3 inch intake/inlet hose
- 3 bar/3.5 bar map sensor with IAT sensor to monitor BAT's (will a 3 bar suffice?)
- EBCS (which brand should I go with?)

Is there anything else I need? Or is it really that simple? Do all the oil and coolant lines just bolt right up? I read that I will have to change the MAP Scalars and Offsets for the new MAP sensor to read accurately, but that shouldn't be a problem. I also read that for an S3 setup the BCS has to be relocated. I'm wondering if that would be the same for the S4. Thanks again!

The BNR S3/S4 turbos comes with new crush washers for the oil feed and coolant feed and drain banjo fittings. The Turbos also come with a little coolant feed adapter so it goes right onto your stock coolant feed. It's really quite straightforward.

Your list is fine. I think a 3-bar is fine unless you plan on going over 40psi. I would get whichever EBCS is offered in the package deals, that's fine.

Do yourself a favor and get 9 new turbo studs and 9 new nuts for said studs. You really don't want to rely on removing and reusing your existing studs/nuts because chances are they are going to be fused together at this point and not reusable. You can get the studs/nuts pretty cheap from Edge if I remember right. Don't get OEM, they are pricey.

You can reuse the metal turbo to exhaust manifold gasket and metal downpipe gasket if you want. I replaced mine, but originals looked fine.

I would recommend getting a new oil drain gasket (the diamond shaped one) that is between the turbo's 2-bolt drain pipe and the turbo. Cheap insurance.

Yes, scale MAP sensor. Zero all wastegate and rebuild boost curve from scratch. Work with a tuner if you are unsure about how to proceed.

The fun part about the s4 package is that it comes with new studs!

ive even been considering selling my 2871 and grabbing an S4. seems like a damn good turbo

I am really trying to fight the urge to buy an s4 right now. I don't need it, s3 is great. Lord, give me strength.

Give in into the S4.
Let the S4 flow through you.

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Let the s4 flow through your intercooler.

Think of it as a $500-600 upgrade if you have an s3... that's the approach I took justifying my purchase.

Mine comes in within the first week of April and my body is ready

I would get a gaurdian angel from Stratified. It is a great failesafe for over boosting and it will work as an updated MAF. I run this with a stratified 3port

Tuning an s4 now with stratified. Installation was pretty straight forward, any questions pm me I'd be more than happy to help. Like dale said your list is good, if you get through rpm will come with ebcs, jbr, 3 bar and adapter. If you do get a 3 inch intake you'll need to relocate the ecu. Also consider getting a new coupler if you have a fmic, where the hot pipe comes in to the turbo sits higher than the stock k04.


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tmillner I run a JBR 3 inch on a BNR S3 and did not have to relocate the battery. Does the S4 fit tighter? I purchased everything through Stratified: BNR S3, 3 port, gaurdian angel, Cobb catted downpipe and Tune. He was great and his prices are very fair and comparable.

Well shucks. I'm looking at an S3 and you might just talk me into an S4 even though I wouldn't necessarily need it.

I think the turbo inlet extends further on the s4. Its a 3 inch inlet rather than the stock size like the s3

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I'm looking at the guardian angel now, really considering it

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It works very well. I plan on getting a cooling mist fail safe for my wmi. It will trigger if there is a pump failure with the gaurdian angel.

S4 all the way

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I'm currently BNR S1. At the time when my ko4 crapped out I didn't have supporting mods for a S3 or big turbo. A little time has passed - lots of parts ordered. I now have all the supporting mods. When I return from my deployment it's S4 time.

stop being a pussy and do it.

As for the OP, honestly if you have the extra $$$ to go with the S4, do it. Very little trade-off between the S3 and S4 and the S4 offers you a little extra head room for future in case you wanted to go further.

S4 with no aux fuel and stock block?

Yeah for now, and at this point I'm using WMI with a small nozzle for added knock protection and low BAT's. How much boost do u think I can get away with up top without aux fueling?
I suppose I may have to lean out a bit depending how much I target.

Thank you, I will definitely follow that advice. Do all vendors sell these turbos with the said seals or is it just a select few? And which vendor sells the most complete kit with the necessary supporting mods?

The reason I ask is because I've looked around and see some that only sell the turbo, and don't mention any other parts.

Whoa really? Studs and nuts? Which vendor?

How do I go about relocating the ECU?

I think corksport sells a battery box ecu relocation kit. Mine is a ghetto set up until i stop being lazy and build a bracket. I had to remove some zip ties and loom to get the slack

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I went through rpm, they sell the 3 bar, harness, ebcs, turbo with gaskets and studs

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Studs/nuts are not necessary.. even if they are fused together, once you start tightening the nut it will break loose and you just need to continue tightening.. but that said they are cheap.

Nothing else is needed for the s4 other than the correct coupler. All the gaskets are provided. It even comes with mani/dp gaskets. I forget the exact term but I would extend the coolant (heater) hose that runs underneath the intake. You'll need it if you have a bigger intake.

Smaller battery box is not needed.

Battery box isn't needed but if you go with a 3 inch intake ecu relocation is, so might as well get on to relocate ecu

I forgot about extended that coolant hose.

I cosign the not needing new studs, mine came out pretty easy, i guess i lost the new ones they sent. But if you can get them you should

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Thanks for the help, I'm definitely leaning more towards replacing the studs and nuts, relocating the ECU, purchasing a full 3 inch intake, and maybe getting a battery box if its required for ECU relocating. I want to accumulate all the required parts before commencing work on the car so I can get it done in one day, as it is my DD. And for extending the coolant hose, should I just buy some longer hose from home depot that can handle heat?

Out of curiosity, how much boost can the S4 generate at high rpm's before it starts becoming inefficient?

I think more than the stock block can handle but I'll let someone smarter than me answer.

I got hose from auto parts store, i think it was 5/8 and a fitting to connect.

Whether you replace studs or not spray with pb blaster to remove. I never liked the stuff but it helped.

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This is the extension I assume.

http://www.hitunedperformance.com/5-...extension-kit/

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I think the S4 can take things beyond the stock fueling capability.

Depends on how clean you want it to look... if relocating the ecu of top of the fuse box is not good enough than you'll need the CS box or small battery box, etc.

The heater hose stuff you can buy from home depot or lowes... just use the link as reference...

Get the s4 and end the questions and doubts! Lol

So I'm not the only person who did this?Attachment 223406

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If you get a smaller battery (51R), the ECU can fit inside of the stock battery box.

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This thread is exactly what I've been bouncing around back and forth in my head for several weeks now. I'll be buying one of these turbos in the next week or two and still can't decide. I'll have about 1100$ to play with so I'm trying to figure out what the best way to go would be. If I go with the s3 I'll have enough to upgrade my intake also which is currently the corksport "stg 2" combo that has the stock turbo sized inlet pipe on the inlet side. If I go with the S4 I'll be stuck with the CS SRI/TIP for a while longer....I know, just buy it all and quit being a pussy right? BUT,I HAVE to start having some will power to quit spending money on this car lol

Does anyone know the gains from a 3 inch intake over cs "stg2"?

My thought was I'd rather re-buy an intake then a turbo if I want bigger

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I upgraded from the corksport to a JBR 3 inch intake on the stock k04 and didn't notice any significant changes. I also had it retuned for the intake size. My friend has the exact same car with exact same mods and we would consistently be even during 3rd to 4th gear pulls. The intake may have offered a slight bump at higher rpm, but in my opinion it was not worth it on a stock turbo. It did motivate me to get the BNR S3 though and that combination works very well.

Does that help voodoo?

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Kinda, I'll probably go s4 and worry about the intake later, I don't want to be kicking myself in the ass in a few months for NOT getting the s4.